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Christopher A. Schuh. Wu, Bruce Y. C., 1980 Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Department of Materials Science and Engineering 2006-03-29T18:29:25Z 2006-03-29T18:29:25Z 2004 http://hdl.handle.net/1721.1/32269 56029570 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004. "June 2004." Includes bibliographical references (leaves 93-96). Nanocrystalline Ni-Co alloys were synthesized using pulsed electrodeposition from a Watts-type bath, and the various plating parameters were systematically varied to examine their effect on the composition, quality, and structure of the resulting deposits. Increasing the pH of the plating bath and/or the average plating current density increased the Ni content of the deposits, but both of these parameters exhibited rather narrow processing windows for the preparation of high-quality deposits. The addition of saccharin during plating was observed both to reduce the crystallographic texture of the Ni-Co alloys and to refine the grain structure. Owing to the low stacking fault energy of Co, many of the alloy deposits exhibited a large density of nanoscale twins. The unique dual-scale grain and nano-twin structure found here caused apparent discrepancies in the grain size measured by XRD and by other microscopy techniques, and also resulted in unique trends in hardness. This thesis lays the groundwork for future tailoring of nanostructured alloys to explore how twins and stacking faults influence their strength and ductility. by Bruce Y.C. Wu. S.M. 100 leaves 3862057 bytes 3860069 bytes application/pdf application/pdf eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Materials Science and Engineering. Synthesis and characterization of nanocrystalline alloys in the binary Ni-Co system/ Thesis application/pdf Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="e18a7fa8-1708-40bd-9010-5a77a339cd91"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Synthesis and characterization of nanocrystalline alloys in the binary Ni-Co system/</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2004</PublicationDate> <Authors> <Author> <DisplayName>Wu, Bruce Y. C., 1980</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Materials Science and Engineering.</Keyword> <Abstract>Nanocrystalline Ni-Co alloys were synthesized using pulsed electrodeposition from a Watts-type bath, and the various plating parameters were systematically varied to examine their effect on the composition, quality, and structure of the resulting deposits. Increasing the pH of the plating bath and/or the average plating current density increased the Ni content of the deposits, but both of these parameters exhibited rather narrow processing windows for the preparation of high-quality deposits. The addition of saccharin during plating was observed both to reduce the crystallographic texture of the Ni-Co alloys and to refine the grain structure. Owing to the low stacking fault energy of Co, many of the alloy deposits exhibited a large density of nanoscale twins. The unique dual-scale grain and nano-twin structure found here caused apparent discrepancies in the grain size measured by XRD and by other microscopy techniques, and also resulted in unique trends in hardness. This thesis lays the groundwork for future tailoring of nanostructured alloys to explore how twins and stacking faults influence their strength and ductility.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>